In recent years, there have been rapid advancements in technology for enabling stereoscopic (three-dimensional) view, and three-dimensional image techniques are starting to become widespread use in movies and televisions. Basically, such three dimensional image techniques utilize binocular parallax which occurs due to spacing between left and right eyes. For example, it is possible to make a viewer see a three-dimensional image by separately displaying, as images exclusive for three-dimensional view, a right eye image and a left eye image so that the right eye image is perceived only by a right eye and the left eye image is perceived only by a left eye.
By the way, according to “3DC Safety Guidelines (revised on Apr. 20, 2010)” set by the 3D Consortium (3DC) Safety Guideline Section, in a case where a viewer who is watching a three-dimensional image sees double or does not sense a three-dimensional effect very much, the viewer should stop watching the image immediately and check if settings of a display device and software are correct, and if the three-dimensional view is unsuccessful (e.g., the viewer sees double or feels a sense of strangeness) even after that, the viewer should stop watching the image.
According to the guidelines, this is because a user of a three-dimensional apparatus utilizing a binocular parallax can feel a three-dimensional effect only after two images from different viewpoints, i.e., right and left eyes are combined in the brain of the user, and if the system is adjusted improperly (e.g., misalignment between left and right optical axes, difference in size between left and right images, difference in color or luminance, misalignment between left and right images in a top-to-bottom direction, mixture of light of a left image and light of a right image (large crosstalk)), the left image and the right image do not combine well, and therefore the user sees double or feels a sense of strangeness, and may suffer eyestrain.
Further, according to the guidelines, even if images to be given to left and right eyes are exchanged with each other, a user (viewer) generally does not notice the exchange contrary to expectation, but since this may cause eyestrain and discomfort, consideration should be given so that such exchange between right and left images does not occur.
In view of the circumstance, it is important to appropriately adjust a three-dimensional effect of a three-dimensional image viewed by a viewer so that the three-dimensional image with an appropriate three-dimensional effect can be viewed by the viewer.
As one means for allowing a viewer to view a three-dimensional image with an appropriate three-dimensional effect, it is very effective to allow the viewer himself to adjust the three-dimensional effect.
For example, Patent Literature 1 discloses an image quality adjustment apparatus which can be suitably applied to a television device and which allows a viewer to adjust an image quality.
This image quality adjustment apparatus allows a viewer to compare an image obtained before an image quality is changed and an image obtained after the image quality is changed. Thus, the viewer can adjust an image quality of an image.
Further, in recent years, a display technique called Picture In Picture is becoming popular. The Picture In Picture is a method of placing a small window inside another window so that a different content can be displayed in the small window. Examples of the Picture In Picture include (i) placing a small window on a corner of a television screen which is displaying a program of one channel so that another channel is displayed in the small window and (ii) displaying a small television image on a corner of a desktop screen of a personal computer.
For example, Patent Literature 2 discloses a navigation system for medical operation utilizing the Picture In Picture. According to this navigation system for medical operation, a position of operating equipment such as surgical instruments that are being used is displayed on biological image information displayed on a display section. This allows a doctor to find a direction in which the operation is performed.
In the Picture In Picture, in a case where a three-dimensional image is displayed on a small window that is displayed in another window, it is important to appropriately adjust a three-dimensional effect of the three-dimensional image viewed by a viewer so that the viewer can view the three-dimensional image with an appropriate three-dimensional effect, as described above.